Method: Object#mp_try

Defined in:

lib/ruby/commons/core_ext/object/try.rb

#mp_try(*a, &b) ⇒ Object

Invokes the public method whose name goes as first argument just like public_send does, except that if the receiver does not respond to it the call returns nil rather than raising an exception.

This method is defined to be able to write

@person.mp_try(:name)

instead of

@person.name if @person

mp_try calls can be chained:

@person.mp_try(:spouse).mp_try(:name)

instead of

@person.spouse.name if @person && @person.spouse

mp_try will also return nil if the receiver does not respond to the method:

@person.mp_try(:non_existing_method) #=> nil

instead of

@person.non_existing_method if @person.respond_to?(:non_existing_method) #=> nil

mp_try returns nil when called on nil regardless of whether it responds to the method:

nil.mp_try(:to_i) # => nil, rather than 0

Arguments and blocks are forwarded to the method if invoked:

@posts.mp_try(:each_slice, 2) do |a, b|
  ...
end

The number of arguments in the signature must match. If the object responds to the method the call is attempted and ArgumentError is still raised in case of argument mismatch.

If mp_try is called without arguments it yields the receiver to a given block unless it is nil:

@person.mp_try do |p|
  ...
end

You can also call mp_try with a block without accepting an argument, and the block will be instance_eval’ed instead:

@person.mp_try { upcase.truncate(50) }

Please also note that mp_try is defined on Object. Therefore, it won’t work with instances of classes that do not have Object among their ancestors, like direct subclasses of BasicObject. For example, using mp_try with SimpleDelegator will delegate mp_try to the target instead of calling it on the delegator itself.

# File 'lib/ruby/commons/core_ext/object/try.rb', line 63

def mp_try(*a, &b)
  mp_try!(*a, &b) if a.empty? || respond_to?(a.first)
end